Slightly improved warning message (#9033)

Author: bsekachev

cvat-ui/src/components/labels-editor/label-form.tsx

@@ -425,7 +425,7 @@ export default class LabelForm extends React.Component<Props> {
                                     className: 'cvat-modal-delete-label-attribute',
                                     icon: <ExclamationCircleOutlined />,
                                     title: `Do you want to remove the "${attr.name}" attribute?`,
-                                    content: 'This action is undone. All annotations associated to the attribute will be removed',
+                                    content: 'This action cannot be undone. All annotations associated to the attribute will be removed',
                                     type: 'warning',
                                     okButtonProps: { type: 'primary', danger: true },
                                     onOk: () => {

cvat-ui/src/components/labels-editor/labels-editor.tsx

@@ -162,7 +162,7 @@ export default class LabelsEditor extends React.PureComponent<LabelsEditorProps,
                 className: 'cvat-modal-delete-label',
                 icon: <ExclamationCircleOutlined />,
                 title: `Do you want to delete "${label.name}" label?`,
-                content: 'This action is undone. All annotations associated to the label will be deleted.',
+                content: 'This action cannot be undone. All annotations associated to the label will be deleted.',
                 type: 'warning',
                 okButtonProps: { type: 'primary', danger: true },
                 onOk() {